<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>

    <style>
      * {
        margin: 0;
        padding: 0;
      }
      button {
        outline: none;
        border-radius: 50%;
        width: 60px;
        height: 60px;
      }
      .tools {
        position: relative;
        display: flex;
        flex-direction: column;
        background-color: #00f;
        width: 60px;
        height: 60px;
      }
      .tools > button {
        position: absolute;
        width: 60px;
        height: 60px;
        border-radius: 50%;
        transform: translate3d(0, -50%, 0) scale(0.8);
        opacity: 0;
        will-change: opacity, transform;
        pointer-events: auto;
      }

      .tools:hover button {
        opacity: 1;
        transform: translateZ(0) scale(1);
        transition: opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1),
          transform 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
      }
      .tools button:nth-child(1) {
        transition-delay: 0s;
      }
      .tools button:nth-child(2) {
        transition-delay: 0.1s;
      }
      .tools button:nth-child(3) {
        transition-delay: 0.2s;
      }
      .tools button:nth-child(4) {
        transition-delay: 0.3s;
      }
      .tools button:nth-child(5) {
        transition-delay: 0.4s;
      }
    </style>
  </head>
  <body>
    <div class="tools">
      <button>A</button>
      <button>A</button>
      <button>A</button>
      <button>A</button>
      <button>A</button>
    </div>
  </body>
</html>
